An oral presentation at the Shallow Defect Level Conference, Amsterdam, associated with ICDS'96

SHALLOW THERMAL DONOR DEFECTS IN SILICON

C. P. Ewels, R. Jones,

Department of Physics, University of Exeter, Exeter, EX4 4QL, UK.

S. Öberg

Department of Mathematics, University of Luleå, Luleå, S95187, Sweden.

J. Miro, P. Deák

Department of Atomic Physics, Technical University of Budapest, Budafoki út 8, H-1111 Budapest, Hungary.

Abstract

An ab initio local density functional cluster program, AIMPRO, is used to examine shallow thermal donor defects in silicon. We find that both nitrogen--oxygen and carbon--oxygen defects can potentially be shallow thermal donors. The bonding of oxygen with interstitial nitrogen in N_i-O_2i is almost `normal' but the O atoms move slightly out of their bond centred sites causing the deep donor level of N_i to become shallow. The defect has properties consistent with those experimentally observed for shallow thermal donors. We also find that a (CH)_i-O_2i defect has very similar electronic properties, and suggest that shallow thermal donors do not have a unique composition.

Keywords: ab initio theory, silicon, oxygen, nitrogen, carbon, hydrogen, shallow thermal donor, STD, defect.

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  C.E. 6.96